Crossbar switch



C GILLINGS ETAL CROSSBAR SWITCH Flled Feb 24 1943 Dec. 1-2, 1944.

IN VENTORS CHARLES GILLINGS LAWRENCE JOHN MURRAY ATTORNEY Patented Dec.12, 1944 CROSSBAR SWITCH Charles Gillings and Lawrence John Murray,

Liverpool, England, assignors, by mesne assignments, to AutomaticElectric Laboratories, Inc., Chicago, 111., a corporation of DelawareApplication February 24, 1943, Serial No. 476,898

- In Great Britain May 28, 1942 3 Claims.

The present invention relates to selecting switch mechanisms for use intelephone or like systems, and is particularly concerned with selectingswitch mechanisms of the crossbar type in which sets of contacts arearranged in such a manner as to form both rows and columns at rightangles to one another.

In one form of such switch there is provided for each of the columns aholding bar member operable under control of an electromagnet, while foreach pair of adjacent rows of contact sets there is provided a Selectingor preparing bar member which'carries a number of flexible or flexiblymounted selecting fingers corresponding to the number of verticalcolumns, and which is operable under control of a pair of electromagnetsto move the selecting fingers into position adjacent the contact sets ofeither of the pair of rows involved.

A IOU-point switch of this kind is provided with ten rows and tencolumns of contact sets and with five two-way horizontal selecting barseach of which will carry ten selecting fingers corresponding to the tenvertical holding bars which will be required and at each of the fiftyintersection points two sets of contacts will be pro vided. In order toselect a given set of contacts the associated horizontal bar will betWisted in a direction to bring its selecting fingers opposite thecontact sets of the particular row of ten in which the required contactset is located and the subsequent operation of the vertical bar commonto all the sets of contacts inthe same column as that in which therequired contact set is located will operate this contact set due to thefact that this will be the only one in the column having a selectingfinger interposed between itself and the vertical bar.

When this contact set has been operated the horizontal bar maybereleased, but the contact set operated will remain held from thevertical holding bar. Subsequently a second or further set of contactscan be operated in-similar manner. provided it is in a difierent columnto the one already operated, but it may be located on the same row.

.On switches of this type it is .possible that if a horizontal bar isactuated in response to say leased the finger may still remain caughtand will not spring into its correct position with rean incoming call ata time when a vertical bar is already operated the selectin finger atthe spect to the contact set operating piece so that the operation ofthe horizontal bar, as far as the column represented by the previouslyoperated vertical bar is concerned, will be ineffective. If thisvertical bar is to be used again and is re-operated, it will not bepossible to effect the necessary connection at the intersection of thevertical and horizontal bars, between the incoming call and a freeoutlet. One way of overcoming this trouble which has been proposed is toshape the actuating members of the contact sets so as to permit of theselecting finger moving to' its proper selecting position under theconditions envisaged. It is the object of the present invention todevise an improved arrangement whereby the above-mentioned trouble maybe overcome.

According to the invention in each of the holding bars of a crossbarswitch mechanism there is provided a plurality of recesses correspondingto the number of selecting bars on the switch and of such dimensionsthat a holding bar on being operated traps the selecting fingers of allunoperated selecting bar-s in its recesses so that the subsequentoperation of a-selecting bar while the holding bar is still actuatedwill be ineffective as far as the selecting finger at the intersectionof such bars is concerned until such time as the holding bar is releasedwhen the selecting finger in question can spring to its operatedposition.

The invention will be better understood from the following descriptionof one method of carrying it into efiect, reference being had to theaccompanying drawing comprising Figs. 1-5.

Of these figures Fig. 1 shows a perspective view of part of themechanism of a known crossbar switch as modified according to theinvention, while Fig. 2 shows a fragmentary side elevational view of themechanism. In both these figures several of the mounting and operating.

members have been broken away for the sake of clarity.

Fig. 3 shows a fragmentary view of two contact set operating pieces toshow their mounting with respect to the mounting frame common to allcontact sets of a column, while Figs. 4 and 5 show the positionsoccupied by the vertical holding bar with respect to the contact setopcrating pieces when this bar is respectivel in its normal and operatedpositions. In all the Figs. 3-5 a selecting finger is shown and isassumed to occupy a normal position.

v and which projects slightly under the mounting plate I2. The verticalholding bar I8 is secured to an L section member I9 one end of whichforms an armature for an actuating electromagnet, not shown, but whichon energising is adapted to twist the member I9, and so advance the barI8 towards all spring sets of the corresponding column.

From Figs. 1, 4 and 5 it will be seen that the vertical holding bar I8is provided with a number of U-shaped recesses corresponding to thenumber of and directly opposite the selecting fingers in thecorresponding column which will be five in the case of a IOU-pointswitch.

With the holding bar in its normal position the selecting pin I6 is freeto swing to a position either between the operating piece I4 oroperating piece I5 and the bar I8, according to the particular directionof twist given to the selecting bar I! and will bridge the U-shaped partof the operating piece concerned as shown in dotted line form in Figs. 1and 2. Hence when the bar I8 is subsequently operated, the selected oneof the two contact sets at the intersection of the horizontal andvertical bars involved will be actuated,

but the contact fingers of all other horizontal bars which will be in anormal position will enter the respective U-shaped slots in the verticalbar in a manner as shown in Fig. 5. The operating edge of the bar willenter the U-shaped part of the operating piece of each of the contactsets at these intersections and so will not operate these other springsets.

If at this stage another horizontal bar is oper-' ated then theselecting finger at the intersection of this horizontal bar and thealready operated vertical bar will remain trapped in the U-shaped recessof the bar I8 and cannot therefore move into engagement with therelevant contact set operating piece.

When the vertical bar is released, and assuming that the secondhorizontal bar is still actuated, the selecting finger concerned willremain in normal position until it disengages from the relevant recessin the vertical bar, any tendency for it to be carried outwardly withthe vertical bar due to frictional coupling with a side of the recessbeing prevented due to the fact that its free end projects under andwould then engage with the mounting plate I2. Hence when the bar becomesclear of the selecting finger the latter will spring into positionagainst the turnedvup stop on the contact set actuating member in theparticular selected row in-readiness for the o eration of the contactset if the same-vertical bar is re-operated.

From the foregoing description. it will be seen that there is thus nopossibility of a selecting finger becoming trapped against the side of acon tact set actuating member due to the actuation of a horizontal barwhen a vertical bar is already operated, the selecting finger at theintersection of the two bars in question being securely held untilsuchtime as the already operated vertical bar is restored to its normalposition.

It will be appreciated that the invention is not limited in scope to theprecise crossbar switching mechanism described and also that the termshorizontal and vertical" are applied to the respective bars and magnets,rows and columns for convenience and do not and are not intended toindicate that such bars, magnets, rows and columns are necessarilyhorizontal and vertical but only to indicate the relationship they wouldbear to each other if the switch was suitably placed, as of course theswitch could be arranged in any desired position.

What we claim as new and desire to secure by Letters Patent is:

1. In a crossbar switch, a preparing bar having a normal position and anoperated position, a holding bar having a normal position and anoperated position, each of said bars being movable from one of itspositions to the other, a member having a normal position and moved toan operated position under the joint control of said bars wheneversaid'preparing bar is moved to its operated position while said holdingbar is at normal and said holding bar thereafter is moved to itsoperated position before said preparing bar returns to normal, means forrestraining said member in its normal position in the event that saidholding bar is moved to its operated position while said preparing baris at normal and said preparing bar thereafter is moved to its operatedposition before said holding bar returns to normal, and a set of circuitcontrolling contacts operated by said member whenever said member is inits operated position.

2. A crossbar switch as claimed in claim 1, wherein said last meanscomprises a recess in said holding bar situated at a point opposite thenormal position of said member, whereby, in the event said holding baris moved to its operated position while said preparing bar is at normal,said member enters said recess, the walls of said recess then preventingmovement of said member to its operated position if said preparing barthereafter should be moved to its operated position.

3. In a crossbar switch, an elongated member having a normal position, aflexible finger supported by said member at right angles to the axis ofsaid member, said member rotatable about its axis thereby to move saidfinger, a second member having one face parallel and normally adjacentto the plane in which said finger ismoved upon rotation of said firstmember, a recess in said second member positioned directly opposite saidfinger when said first member is in its normal position, means formoving said second member toward said finger, said second memberefiective to engage and move said finger only if said first member isofi-normal at the time of such movement of said second member, a set ofcircuit controlling contacts operated by said finger upon movementthereof by said second member, said recess effective, if said firstmember is at normal when said second member is moved toward said finger,to partially encompass said finger and thereby prevent subsequentmovement of said finger in the event that said first member thereafteris rotated before said second member returns to normal.

CHARLES GILLINGS. LAWRENCE JOHN MURRAY.

